Immobilization Of Indigenous Lactic Acid Bacteria D-210 β-galactosidase with Natrium Alginate and Its Potential in UHT milk

Abstract

Lactose intolerance is a symptom who cannot produce the β-galactosidase enzyme (lactase) an enzyme that catalyzes hydrolysis of lactose into glucose and galactose, in their digestive system. In most cases this causes symptoms which may include abdominal bloating and cramps, flatulence, diarrhea and nausea. Immobilization of Indigenous Lactic Acid Bacteria strain D-210 β-galactosidase with natrium alginate and its potential in UHT milk has not been reported yet. Indigenous Lactic Acid Bacteria strain D-210 was found as bacteria producing β-galactosidase which was culture in MRS (Mann Rogosa Sharpe) and substrate lactose 3%. The β-galactosidase was dialyzed for getting the partial pure. The research results showed that the optimum production of β-galactosidase in Indigenous Lactic Acid Bacteria Strain D-210 was reached on 24 hours with activity 26.605 U/ml and total activities was 27.669 U, and Indigenous Lactic Acid Bacteria Strain D-210 optimum growth was reached on 24 hours with optimum optical density 1.984 and amount of cell was 1.81x10-8 cell/ml. The total activities partial purification of crude β-galaktosidase was 138.396 U, total activities after presipitation with amonium sulfat the total activities was 87.030 U and total activities after dialysis was 50.420 U. The inhibitors of β-galaktosidase were Hg and Cu with relative activities were 56.82% and 1.04%, while the activators were Mg,Mn,Ca,Co,Zn. Kinetic parameter of enzyme showed that the values of Km: 0.491 mM and Vmax:0.093 μmol/minute (free β-galactosidase), and values of Km:15.54 mM and Vmax 0.474 μmol/minute (immobilized β-galactosidase) . The optimum activity of the free β-galactosidase was reached on pH: 6.5 with activity 252.341 U/ml, and temperature: 45 oC with activity 180.093 U/ml. The optimum concentration of Na alginate for immobilized cell and β-galactosidase were 2% and 3% respectively. The concentration of Na alginat used for hydrolysis lactose in cell was 12% with the released total product 58.884 μmol and for the β-galactosidase was 20% with the released total product 91.752 μmol. The optimum activity of the immobilized β-galactosidase was reached on pH:6 with activity 40.428 U/ml, and on temperature: 40 oC with activity 41.194 U/ml. The optimum potential of cell imobilized and β-galactosidase for lactose hidrolysis in UHT milk were reached for 6 hours and 18 hours with relative activity 76.72% and 62.78% respectively. Repeated use of cell and enzyme β-galactosidase immobilized was 6 times with the use of relative hydrolisis activity were 39.52% and 53.68% respectively.